Method and apparatus for condensing vapors



June 13, 1933;

w. E. LuMMus METHOD AND APPARATUSFOR CONDENSING VAPORS Filed March 9, 1931 venfor' fWmfi. I

Wibw-JJ Patented June 13, 1933 UNITED STATES PATENT OFFICE WALTER E. LUMMUS, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE LUMMUS COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF DELAWARE :METHOD'AND AIPPABATUS FOR CONDENSING VAPORS Application filed March 9, 1931. Serial N0. 521,185.

The present invention relates to methods and apparatus for condensing vapors, and more particularly for condensing hydrocarbon oil vapors.

The condensation of a light hydrocarbon oil fraction presents some difficulties in that the fraction does not consist of aumtary product but rather a mixture of components having a considerable range of bolhng points. The more volatile components known as the permanent gases are not condensible by themselves at ordinary pressures and cooling water temperatures, although they may dissolve readily in liquid hydro- 5 carbons of higher boiling points. This solution of the so-called permanent gases in higher boiling components may take place at temperaturesconsiderably in excess of the condensing temperatures of the gases, provlded 0 suitable proportions and sufliclently good contact between the gases and the liquid components are maintained. The capacity of oils to absorb gases is greater, the lower the temperature of the oil. In condensing a lighthydrocarbon fraction such as gasoline by the usual surface condensing method, no provision for liquefaction of the gases 1s made; on the contrary, the conditlons are such that fractional separation of the permanentgases from the heavier condenslble liquid is enhanced. Thus, upon entrance into the condenser, the vapors of higher boiling point tend to condense in greater proportion than those of lower boiling po nt, and the uncondensed lighter vapors'rise immediately away from the condensate. Th1s elective or progressive condensation com mes until, if the condenser is large enough, prac tically all ofthe components having boiling poin s higher than the temperature of the cooling water are condensed, but important values in the form of the gases and lighter vapors are completely. separated from the condensed liquidand are discharged from the condenser in such form that they can be liqu'efied only with great difiiculty as by refrigeration and compremion or by absorption in an inordinately large volume of oils." In many cases, it is considered more economical to waste the gases than to attempt to liquefy them.

Theobject of the present invention is to provide a method and apparatus whereby vapors, although comprising a mixture of components of difierent condensing points,

may be more completely condensed without appreciable fractionation and by the use of a Hnniimum amount of absorbing or cooling With this object in view, the present invention consists of certain novel features of construction and modes of operation hereinafter described and particularly defined in the claims. y

In the accompanying drawing, Fig. 1 is a sectional elevation of the preferred form of condenser'applied to a distilling'or rectifying tower, and Fig. 2 is a detail of a bubble tube.

In the illustrated embodiment of the in vention, the condenser is mounted on the top of a rectifying tower of conventional form which is indicated generally at 2. The condenser 4' comprises an outer shell and a central inner pipe 6 through which the vapors vapors with a minimum variation in liquid level, and atthe lower end an enlarged serrated l:' 1.13 to provide a-large area of bubbling contact of vapors with liquid. The condenser is closed at the bottom by an annulaiimperforate deck 14. Condensing liquid, such as water, is admitted to the top: deck from a supply 16 through a pipe 18' controlled by a valve .20. The mixture of condensing liquid and condensed vapors is removed from the bottom deck 14 through a pipe 22 which leads into a decanter 24. Any uncondensed vapors leave the decanter through a pipe 26 and may be passed to a second condenser or to a refrigerator for further condensation. The liquid condensate is decanted from the water and is collected in a bottle 28 from which part of the condensate is drawn through a pipe 30 as a product and the remainder may be all or partly returned through a pipe 32 to the top of the rectifying column to act as reflux. The amount of reflux returned to the column and hence the amount of product removed through the pipe 30 is controlled by a valve 34 in the pipe 30.

Provision is made for cooling the liquid and vapors in the several stages. This may be done in any suitable manner but preferably by means of cooling coils 36 immersed in the liquid on each deck. The coils are provided with external connections by which cold water may be circulated there-through.

In operation, the vapors collect in the space in the top of the condenser and pass down through the pipes 12 to bubble successively through the liquids standing on the several decks. As the vapors are condensed, the liquid overflows into the pipes 12 and carries with it the condensed and dissolved vapors.

It will be noted that the condenser operates upon the principle of parallel flow of liquid and vapors. In the passage through the condenser, the condensing liquid is heated and the vapors are cooled. Assuming that the coils 36 are not used, the final temperature of the liquid drawn off from the lowest deck will be intermediate to the initial temperatures of the cooling liquid and the vapors. Thus if the vapors ascending from the rectifying column are at a temperature of 250 and the condensing liquid at a temperature of 90, the temperature of the liquid entering the decanter will have an intermediate value depending upon the relative quantities of the vapors and cooling liquid. This exit'temperature' of the liquid is usually somewhat igher than would be obtained with countercurrent cooling of the same volumes of vapor and liquid but a more complete liquefaction is obtained because the liquid contains dissolved components which if separated from the mixture would condense only at temperatures considerably below the temperature of the mixture. Thus a large quantity of the permanent gases which tend of themselves to separate from the mixture are largely absorbed in the oils. It will be seen, therefore, that the purpose of the cooling liquid is not only to effect condensation itself, but also to cool the components of higher condensing points to such temperatures that they have a marked dissolving action on the so-called permanent gases;

The above explanation assumes the cooling coils 36 are not used and the condenser is in fact very effective even when such additional cooling means are not employed. It Will be noted, however, that with the high degree of contact afforded by the bubble tubes 12, practically all of the condensing act on will occur in the first stages. The cooling coils are therefore used for the purpose of maintaining the liquid in successive stages at low temperatures so as further to enhance the solubility of the lighter fractions in the oil. Although cooling means are shown in the drawing as applied to each stage, they may, if desired, be omitted from the upper stages and used only in the lower stages.

Although the preferred cooling liquid introduced through the pipe 18 has been described as water, which commends itself because of its availability, it will be understood that the invention is not limited to the use of water. In fact, it may be desirable in some instances to employ an oil which will act not only as a cooling medium, but will in itself tend to dissolve a considerable proportion of the gases.

The invention having been described, what is claimed is:

1. A condenser for light hydrocarbon vapors comprising a series of decks, tubes in each deck leading to the deck next below and arranged to maintain liquid in each deck, means for passing condensing liquid and vapors downwardly through the tubes to per mit bubbling of the vapors through the liquid on each deck, and means for cooling the liquid in different stages.

2. The method of condensing vapors having a wide range of boiling points which consists in passing condensing liquid and the vapors together downwardly through a plurality of condensing stages, maintaining a level of liquid in each stage, permitting the vapors to bubble through the liquid in each stage, and cooling the liquid in different stages.

3. The method of condensing light hydrocarbon vapor mixtures including some components having boiling points lower than the temperature of the cooling liquid which consists in passing the cooling liquid and the vapors together downwardly through a succession of condensing'stages, maintaining a level of liquid in each stage, permitting the vapors to bubble through the liquid in each stage, and cooling the liquid in the several stages.

4. The method of condensing light hydrocarbon vapor mixtures including some socalled permanent gas components having condensing points lower than the temperature of the cooling liquid which consists in passing the cooling liquid and the vapors together lltl III

downwardly through a succession of condensmg stages, mamtammg a level of liquid in each stage, and permitting the vapors to bubble through the liquid in each stage to condense the vapors of higher boiling point and to permit absorption of the gases in the materials thus condensed.

carbon vapor mixtures inclu some socalled permanent gas components aving condensing points lower than the temperature of the cooling liquid which consists in passing the cooling liquid and the vapors to ther downwardly through a succession 0 con (lensing stages, maintaining a level of liquid in each stage, and permittmg the vapors to bubble through the liquid in each stage to condense the vapors of higher boiling point and to permit absorption of the gases in the materials thus condensed, and cooling the v 1i uid in the several stages.

n testimony whereof I have signed my name to this specification.

WALTER E. LUMLIUS.

5; The method of eondensingllight hydro- 

